Output Impedance Diffusion into Lossy Power Lines

Output impedances are inherent elements of power sources in the electrical grids. In this paper, we give an answer to the following question: What is the effect of output impedances on the inductivity of the power network? To address this question, we propose a measure to evaluate the inductivity of a power grid, and we compute this measure for various types of output impedances. Following this computation, it turns out that network inductivity highly depends on the algebraic connectivity of the network. By exploiting the derived expressions of the proposed measure, one can tune the output impedances in order to enforce a desired level of inductivity on the power system. Furthermore, the results show that the more "connected" the network is, the more the output impedances diffuse into the network. Finally, using Kron reduction, we provide examples that demonstrate the utility and validity of the method

Phase protection system for ac power lines

The system described provides protection for phase sensitive loads from being or remaining connected to ac power lines whenever a phase reversal occurs. It comprises a solid state phase detection circuit, a dc power relay circuit, an ac-to-dc converter for energizing the relay circuit, and a bistable four terminal transducer coupled between the phase detection circuit and the power relay circuit, for controlling both circuits

General design of multiway multisection power dividers by interconnecting two-way dividers

It is common practice to design multiway power dividers by interconnecting two-way power dividers. Transmission lines are used to link the two-way dividers. This paper investigates the performance of the interconnected power divider and the effects of the interconnecting transmission lines. In particular, it will be shown that the performance of multiway dividers constructed by interconnecting even-number-section two-way dividers deteriorates significantly as the number of output ports increases. The interconnecting lines can be used to improve the performance of such dividers

Covariance of the One-Dimensional Mass Power Spectrum

We analyse the covariance of the one-dimensional mass power spectrum along lines of sight. The covariance reveals the correlation between different modes of fluctuations in the cosmic density field and gives the sample variance error for measurements of the mass power spectrum. For Gaussian random fields, the covariance matrix is diagonal. As expected, the variance of the measured one-dimensional mass power spectrum is inversely proportional to the number of lines of sight that are sampled from each random field. The correlation between lines of sight in a single field may alter the covariance. However, lines of sight that are sampled far apart are only weakly correlated, so that they can be treated as independent samples. Using N-body simulations, we find that the covariance matrix of the one-dimensional mass power spectrum is not diagonal for the cosmic density field due to the non-Gaussianity and that the variance is much higher than that of Gaussian random fields. From the covariance, one will be able to determine the cosmic variance in the measured one-dimensional mass power spectrum as well as to estimate how many lines of sight are needed to achieve a target precision.Comment: 13 pages, 8 figures, MNRAS accepte

Developments in space power components for power management and distribution

Advanced power electronic components development for space applications is discussed. The components described include transformers, inductors, semiconductor devices such as transistors and diodes, remote power controllers, and transmission lines

Electrocution of raptors at power lines in Central Kazakhstan

Along three transects of medium voltage power lines in the steppe of Central Kazakhstan, surveys for bird casualties were carried out in summer 2006 in order to estimate the quantitative and qualitative impact of power lines on bird mortality in this area. In total, 409 dead birds of 34 different species were found. Raptors represented 44 % of the total (179 individuals, 10 species). Most of them died due to electrocution. The proportion of raptors strongly varied between early and late summer, the increase in August suggests that especially young birds are prone to electrocution. The density of raptor casualties varied from 0.1 to 7.6 birds per line km and month. Adverse effects of power lines on bird life could be avoided by changing the pole construction (use of suspended insulators) or protective measures (e. g. caps).Zur Bestimmung des qualitativen und quantitativen Ausmaßes des Stromtodes von Vögeln in Zentralkasachstan wurden im Sommer 2006 Transektzählungen entlang von drei Mittelspannungsleitungen in dieser Region durchgeführt. Insgesamt wurden 409 tote Vögel (34 verschiedene Arten) gefunden, davon 44 % Greifvögel (179 Individuen, 10 Arten). Der Großteil starb durch Elektrokution. Der Anteil der Greifvögel variierte stark zwischen Früh- und Spätsommer. Der Anstieg im August lässt vermuten, dass Jungvögel besonders gefährdet sind. Die Greifvogeldichte betrug zwischen 0,1 und 7.6 Vögel pro Transekt-km und Monat. Durch veränderte Mastenkonstruktion (hängende Isolatoren) oder Schutzmaßnahmen (isolierende Hauben) kann viel zum Vogelschutz beigetragen werden

Classification of critical aging segments of power transmission lines

An Analytic Hierarchy Process (AHP) approach been used for analysis, comparison and classify the quality of several parameters that affect the conductor thermal ratings. The method is based on pairwise comparison between several factors that affect the alternatives in a hierarchical structure. The thermal ratings of power transmission lines is basically based on the maximum permissible temperature of the conductors. Conductor can lose their tensile strength due to thermal load or annealing. This paper analysis thermal aging using known characteristics of transmission conductor, load information and weather data. By analyzing the conductor temperatures, aging due to loss of conductor tensile strength is estimated at individual locations along the transmission corridor. The proposed methodology is illustrated using a case study analyzing a power transmission line in Kluang, Johor. This information is important for transmission network operating procedures, scheduling of line inspections, maintenance, or reconductoring

Stabilizing control for power converters connected to transmission lines

This paper proposes a switching control strategy for the set-point stabilization of a power converter connected via a transmission line to a resistive load. The strategy employs a Lyapunov function that is directly based on energy considerations of the power converter, as well as of the transmission line described by the telegraph equations. The proposed stabilizing switching control still allows a certain freedom in the choice of the control law, a comparison between a maximum descent strategy and a minimum commutation strategy being discussed on a simple example.